Should we treat individuals homozygous for HFE p.Cys282Tyr with ferritin 300-1000 μg/L?

Chelating Polymers for Hereditary Hemochromatosis Treatment

Hemochromatosis (iron overload) encompasses a group of diseases that are characterized by a toxic hyperaccumulation of iron in parenchymal organs. Currently, only few treatments for this disease have been approved; however, all these treatments possess severe side effects. In this study, a paradigm for hemochromatosis maintenance/preventive therapy is investigated: polymers with negligible systemic biological availability form stable complexes with iron ions in the gastrointestinal tract, which reduces the biological availability of iron. Macroporous polymer beads are synthesized with three different iron-chelating moieties (benzene-1,2-diol, benzene-1,2,3-triol, and 1,10-phenanthroline). The polymers rapidly chelate iron ions from aqueous solutions in vitro in the course of minutes, and are noncytotoxic and nonprooxidant. Moreover, the in vivo biodistribution and pharmacokinetics show a negligible uptake from the gastrointestinal tract (using ¹²⁵ I-labeled polymer and single photon emission computed tomography/computed tomography), which generally prevents them from having systemic side effects. The therapeutic efficacy of the prepared polymers is successfully tested in vivo, and exhibits a significant inhibition of iron uptake from the gastrointestinal tract without any noticeable signs of toxicity. Furthermore, an in silico method is developed for the prediction of chelator selectivity. Therefore, this paradigm can be applied to the next-generation maintenance/preventive treatment for hemochromatosis and/or other diseases of similar pathophysiology.

Haemochromatosis

Haemochromatosis is defined as systemic iron overload of genetic origin, caused by a reduction in the concentration of the iron regulatory hormone hepcidin, or a reduction in hepcidin-ferroportin binding. Hepcidin regulates the activity of ferroportin, which is the only identified cellular iron exporter. The most common form of haemochromatosis is due to homozygous mutations (specifically, the C282Y mutation) in HFE, which encodes hereditary haemochromatosis protein. Non-HFE forms of haemochromatosis due to mutations in HAMP, HJV or TFR2 are much rarer. Mutations in SLC40A1 (also known as FPN1; encoding ferroportin) that prevent hepcidin-ferroportin binding also cause haemochromatosis. Cellular iron excess in HFE and non-HFE forms of haemochromatosis is caused by increased concentrations of plasma iron, which can lead to the accumulation of iron in parenchymal cells, particularly hepatocytes, pancreatic cells and cardiomyocytes. Diagnosis is noninvasive and includes clinical examination, assessment of plasma iron parameters, imaging and genetic testing. The mainstay therapy is phlebotomy, although iron chelation can be used in some patients. Hepcidin supplementation might be an innovative future approach.